Question

Explain the process of microtubule assembly and disassembly. What role does dynamic instability play in the cell?

Answer 1

Microtubules are the one of the important components of cytoskeleton. They are the rigid hollow rods measuring about 25nm in diameter. Thye are made up of a protein called tubulin. The tubulin protein contains two subunits - tubulin and tubulin. The microtubules are assembled by polymerization. The microtubules contain polarity - the fast growing end (+) and the slow growing end (-). The polymerization of microtubules requires energy as in case of actin molecules. The energy for polymerization of microtubules is provided by GTP. The GTP binds to + end of microtubules and adds molecules continuously to polymerize (assembly). The GTP later on undrgoes hydrolysis to GDP and this releases the microtubule molecules from - end causing disassembly.

In microtubules, GTP hydrolysis also results in the behavior known as dynamic instability, in which individual microtubules alternate between cycles of growth and shrinkage of cell exhibiting the assembly and disassembly activities.